1. Field of the Invention
This invention relates to a registration method for a biometrics authentication system, a biometrics authentication system, and a program for same, which use the characteristics of a portion of the human body to perform individual authentication, and in particular relates to a registration method for a biometrics authentication system, a biometrics authentication system, and a program for same, which detect the characteristics of the palm of the hand by non-contact means to acquire biometrics information.
2. Description of the Related Art
There are numerous portions of the human body, such as fingerprints and toe-prints, the retinas of the eyes, facial features, and blood vessels, which enable discrimination of individuals. With advances in biometrics in recent years, various devices have been proposed for authentication of individuals by identifying biometrics features of such portions of the human body.
For example, blood vessels of the palm and fingers, and palm-prints and fingerprints, provide a comparatively large amount of individual characteristic data, and so are suitable for ensuring reliability in individual authentication. In particular, blood vessel (vein) patterns remain unchanged throughout life from infancy, and are regarded as being completely unique, and so are well-suited to individual authentication. FIG. 18 through FIG. 21 explain conventional palm authentication techniques. As shown in FIG. 18, at the time of registration or authentication, the user brings the palm of the hand 110 into proximity with an image capture device 100. The image capture device 100 emits near-infrared rays, which are incident on the palm of the hand 110. The image capture device 100 uses a sensor to capture near-infrared rays rebounding from the palm of the hand 110.
As shown in FIG. 19, hemoglobin in the red corpuscles flowing in the veins 112 has lost oxygen. This hemoglobin (reduced hemoglobin) absorbs near-infrared rays at wavelengths near 760 nanometers. Consequently when near-infrared rays are made incident on the palm of a hand, reflection is reduced only in the areas in which there are veins, and the intensity of the reflected near-infrared rays can be used to identify the positions of veins.
As shown in FIG. 18, the user first uses the image capture device 100 of FIG. 18 to register vein image data of the palm of his own hand in a server or on a card. Then, in order to perform individual authentication, the user employs the image capture device 100 of FIG. 18 to read the vein image data of his own hand.
The individual is authenticated by comparing the patterns of veins in the registered vein image retrieved using the user's ID and in the vein verification image thus read. For example, on comparing the vein patterns in the registered image and a verification image as in FIG. 20, the individual is authenticated as the individual in question. On the other hand, upon comparison of the vein patterns in a registered image and in a verification image as in FIG. 21, the individual is not authenticated (see for example Japanese Patent Laid-open No. 2004-062826).
In such non-contact detection of biometrics information, the body part can be freely moved with respect to the image capture device 100, and in particular the hand can be freely moved. On the other hand, in order to perform accurate detection, the body part for detection 110 must be positioned within the image capture range of the image capture device 100. Methods to achieve this have been proposed in which the position and orientation of the hand is detected from a captured image, and when accurate image capture is not possible, a display or voice output is employed to convey the inappropriateness of the position or orientation of the hand (see for example WO04/021884). In this proposed method, an image of the entire hand is captured and is compared with the average registered hand shape to detect the position and orientation of the hand.
In registration of such biometrics information, methods have been proposed in which, when registering fingerprint data, fingerprint data is detected a plurality of times and common characteristic data is extracted from the plurality of sets of fingerprint data, and this common characteristic data is registered (see for example Japanese Patent Laid-open No. 01-263775 and Japanese Patent Laid-open No. 11-232459). Through such methods, the effect on registered data of detection noise and of changes in fingerprint shape due to differences in finger pressure can be prevented.
In such non-contact detection of biometrics information, detection is by non-contact means, and moreover the body part, and in particular the hand, can move freely. On the other hand, in order to perform rapid biometrics authentication, it is necessary that image capture be performed frequently, and that appropriate images be detected and output to the registration/authentication process. Hence in methods which compare the images of entire hands, time is required to detect the position and orientation of the hand, and moreover the size of the sensor in the image capture device is increased, making such methods unsuitable when rapid detection or small equipment sizes are demanded.
Further, in conventional methods in which common characteristics are extracted and registered, noise due to the biometrics detection device and differences in detection states at the time of biometrics detection can be excluded. But when registering common data, there is the possibility that the individual biometrics characteristic data sets actually obtained will not exactly match the registered data, and that the amount of characteristic data will differ from the amount of characteristic detection data. Hence when comparing verification data with registered data at the time of authentication, it may be difficult to perform verification with high accuracy.
Moreover, because the actual data is biometrics data, changes in physical condition must also be taken into account. And when registering common data, if there are differences in physical condition at the time of authentication and at the time of registration, even when the individual is the same, authentication as the same individual may not be possible, so that problems may occur. For example, in authentication using vein patterns, there are numerous factors resulting in fluctuations, among them the pulse rate, the timing of image capture, and the manner in which the hand is presented.
Hence there are impediments to application to equipment in general for use at any time, anywhere, by anyone. But if verification rates are not satisfactory, and problems arise for biometrics reasons, widespread adoption by both users and by equipment manufacturers is impeded.